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.TH INET_ADDR 3XNET "Jun 10, 2002"
.SH NAME
inet_addr, inet_network, inet_makeaddr, inet_lnaof, inet_netof, inet_ntoa \-
Internet address manipulation
.SH SYNOPSIS
.LP
.nf
\fBcc\fR [ \fIflag\fR ... ] \fIfile\fR ... \fB-lxnet\fR [ \fIlibrary\fR ... ]
#include <arpa/inet.h>

\fBin_addr_t\fR \fBinet_addr\fR(\fBconst char *\fR\fIcp\fR);
.fi

.LP
.nf
\fBin_addr_t\fR \fBinet_lnaof\fR(\fBstruct in_addr\fR \fIin\fR);
.fi

.LP
.nf
\fBstruct in_addr\fR \fBinet_makeaddr\fR(\fBin_addr_t\fR \fInet\fR, \fBin_addr_t\fR \fIlna\fR);
.fi

.LP
.nf
\fBin_addr_t\fR \fBinet_netof\fR(\fBstruct in_addr\fR \fIin\fR);
.fi

.LP
.nf
\fBin_addr_t\fR \fBinet_network\fR(\fBconst char *\fR\fIcp\fR);
.fi

.LP
.nf
\fBchar *\fR\fBinet_ntoa\fR(\fBstruct in_addr\fR \fIin\fR);
.fi

.SH DESCRIPTION
.sp
.LP
The \fBinet_addr()\fR function converts the string pointed to by \fIcp\fR, in
the Internet standard dot notation, to an integer value suitable for use as an
Internet address.
.sp
.LP
The \fBinet_lnaof()\fR function takes an Internet host address specified by
\fIin\fR and extracts the local network address part, in host byte order.
.sp
.LP
The \fBinet_makeaddr()\fR function takes the Internet network number specified
by \fInet\fR and the local network address specified by \fIlna\fR, both in host
byte order, and constructs an Internet address from them.
.sp
.LP
The \fBinet_netof()\fR function takes an Internet host address specified by
\fIin\fR and extracts the network number part, in host byte order.
.sp
.LP
The \fBinet_network()\fR function converts the string pointed to by \fIcp\fR,
in the Internet standard dot notation, to an integer value suitable for use as
an Internet network number.
.sp
.LP
The \fBinet_ntoa()\fR function converts the Internet host address specified by
\fIin\fR to a string in the Internet standard dot notation.
.sp
.LP
All Internet addresses are returned in network order (bytes ordered from left
to right).
.sp
.LP
Values specified using dot notation take one of the following forms:
.sp
.ne 2
.na
\fB\fBa.b.c.d\fR\fR
.ad
.RS 11n
When four parts are specified, each is interpreted as a byte of data and
assigned, from left to right, to the four bytes of an Internet address.
.RE

.sp
.ne 2
.na
\fB\fBa.b.c\fR\fR
.ad
.RS 11n
When a three-part address is specified, the last part is interpreted as a
16-bit quantity and placed in the rightmost two bytes of the network address.
This makes the three-part address format convenient for specifying Class B
network addresses as \fB128.\fR\fInet\fR.\fIhost\fR.
.RE

.sp
.ne 2
.na
\fB\fBa.b\fR\fR
.ad
.RS 11n
When a two-part address is supplied, the last part is interpreted as a 24-bit
quantity and placed in the rightmost three bytes of the network address. This
makes the two-part address format convenient for specifying Class A network
addresses as \fInet\fR\fB\&.\fR\fIhost\fR.
.RE

.sp
.ne 2
.na
\fB\fBa\fR\fR
.ad
.RS 11n
When only one part is given, the value is stored directly in the network
address without any byte rearrangement.
.RE

.sp
.LP
All numbers supplied as parts in dot notation may be decimal, octal, or
hexadecimal, that is, a leading 0x or 0X implies hexadecimal, as specified in
the \fIISO C\fR standard; otherwise, a leading 0 implies octal; otherwise, the
number is interpreted as decimal.
.SH USAGE
.sp
.LP
The return value of \fBinet_ntoa()\fR may point to static data that may be
overwritten by subsequent calls to \fBinet_ntoa()\fR.
.SH RETURN VALUES
.sp
.LP
Upon successful completion, \fBinet_addr()\fR returns the Internet address.
Otherwise, it returns (\fBin_addr_t\fR)(\(mi1).
.sp
.LP
Upon successful completion, \fBinet_network()\fR returns the converted Internet
network number. Otherwise, it returns (\fBin_addr_t\fR)(\(mi1).
.sp
.LP
The \fBinet_makeaddr()\fR function returns the constructed Internet address.
.sp
.LP
The \fBinet_lnaof()\fR function returns the local network address part.
.sp
.LP
The \fBinet_netof()\fR function returns the network number.
.sp
.LP
The \fBinet_ntoa()\fR function returns a pointer to the network address in
Internet-standard dot notation.
.SH ERRORS
.sp
.LP
No errors are defined.
.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(7) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	Standard
_
MT-Level	MT-Safe
.TE

.SH SEE ALSO
.sp
.LP
.BR endhostent (3XNET),
.BR endnetent (3XNET),
.BR attributes (7),
.BR standards (7)
